PURPOSE: To prevent the collision of trucks with each other and to prevent the slip of the steel slab, by changing the moving speeds of respective trucks in charging or retreating of heated steel material in a divided walking beam type heating furnace composed of trucks for charging, heating, and discharging zones.

CONSTITUTION: Trucks in a walking beam type heating furnace are divided into charging zone trucks A, heating zone trucks B, and discharging zone trucks C. A connecting tool 11 composed of a convex material 9 and a concave material 10 is equipped between the truck B and C, and cylinders 12W14 for the forward and backward movement are attached to respective trucks, and every trucks are equipped with operating mechanisms for walking such as forward and backward movement and upward and downward movement. In the movement of interlocked trucks A, B, and C, the trucks are moved through the connecting tool 11, so that the convex material 9 and the concave material 10 are connected, hence no plays are formed inspite of a space S thereby preventing the slip of the slab 8. In advancing the truck A at the same time with B, C, setting of speed difference for the cylinder 12 in such a way that the speed of truck A is a little smaller than those of trucks B, C allows to prevent the collision of the truck A to the truck B.